S. Himmelstein | June 28, 2022
The reliable grid integration of wind and solar energy sources requires making sure the grid is protected if there is a fault, such as a short circuit. U.S. National Renewable Energy Laboratory (NREL) researchers provide guidance on how to solve this challenge and maintain power systems protection with higher levels of inverter-based renewable energy generation in future grids.
The most typical type of fault is a short circuit, which can occur when two wires touch or when a tree touches a wire. This causes the generators to produce a big surge of electrical current, resulting in fault current and potentially lead to fires and equipment damage.
Fault current is primarily produced by synchronous generators in fossil, nuclear and hydroelectric plants, which can inherently produce large amounts of current. However, inverter technology is not typically designed to produce large amounts of fault current, so in a grid with high levels of solar photovoltaics and wind, the power system may need to find new ways to provide fault protection.
A fault can occur in any part of the grid, so protection equipment is required that is suitable for the voltage and current levels in each section. Source: NREL
A document issued by NREL provides a brief overview of system protection and fault current in maintaining a safe power system. The report explains why alternative approaches may be needed with increasing deployment of wind and solar generation, and it addresses various approaches to maintaining system protection in the evolving grid. These include continued use of synchronous machines, adding fault current capacity to inverter-based resources, and deploying sensors to measure the flow of current at many points on the grid and comparing the measurements to what they would be under a range of normal conditions.